Portable and fixed gas detection systems are necessary devices for use in all forms of industry, manufacturing and first responder situations where toxic gases may be present. Having reliable, accurate gas detection systems in these situations are invaluable for keeping workplaces and employees safe from explosions, fire, suffocation, and other injuries related to the inhalation of toxins. Portable gas detection monitors allow for testing for dozens of gases wherever and whenever there is a need to test air quality. Fixed gas detection systems serve as a constant source of protection, continuously monitoring air quality and providing active feedback for review.
Optical systems used along with chemically-treated paper tape are known in the art of gas detection systems. For example, some low level gas detection systems have been used in the detection of gases by flowing gas to the detection tape, while simultaneously reading reflected photons in the grey scale to interpret gas concentration.
In known gas detection systems, chemically-impregnated tape is placed in series with the flow of gas and the optical system with a fixed green, blue or red LED light depending on expected color change for best grey scale change on photodiode. The photodiode measures a reflection from the treated tape. When the chemically-impregnated tape is exposed to the gas flow and the target gas is present, the tape discolors causing less photons to reach the photodiode. A microprocessor is used to analyze the results from the photodiode to determine the type and concentration of the gas exposed to the tape.
Typically, a family of gases will cause this discoloration on chemically-impregnated tape, however, making it difficult to detect exactly which type or species of gas was causing the discoloration. For example, a tape impregnated to respond to Hydride gases will respond differently to different Hydride family gases, producing different colors. However, initial optic systems could not differentiate different colors, and thus, the particular species of gas could not be detected, resulting in potentially an inaccurate response to the particular gas.
Current optic systems used in gas detectors typically use an adjustable LED RGB (Red, Green, and Blue) light source to scan or produce different source colors, i.e., scan different wavelengths, and using a standard photo diode and wavelength spectrum analyzer, try differentiate the paper tape stain colors, and thus, determine a specific gas. This process has not proven to be effective because of the time it takes to scan, LED RGB source tolerances, expense, and the fact the color is constantly changing during gas to gas exposure. The current LED RGB scanning source, photodiode, wavelength analyzer scanning system has not proven to increase sensitivity, or offer an efficient or cost effective solution to differentiate species on a chemically impregnated paper tape. The result is potentially invalid interpretation of the actual incident, with no visual recorded evidence.
Therefore, there is a continuing, ongoing need for real-time colorimetric gas detectors that can differentiate specific colors as they change on the impregnated media, such as a treated tape, thereby providing more accurate detection of specific gases. Additionally, a need exists for an improved system, method and gas detection apparatus that not only differentiates colors for the detection of different species of gases on same media, but visually records and saves the event for review and critical record keeping. As there is typically an investigation after an event, it is important to have a record of the event so that verification of whether it was a true gas alarm or a false gas alarm can be determined.
A need further exists for an improved system, method and apparatus for the detection of gases in real-time, which is useful as a safety and evacuation device in a variety of industries and manufacturing facilities.
Moreover, a need exists for an improved system, method and apparatus for efficient, accurate and cost-effective detection of specific species of gases on a chemically-impregnated media during a gas detection event.
Additionally, a need exists for an improved system, method and apparatus for capturing and recording the chemically-impregnated media color change during its exposure to the subject gas or gases. The advantage offered by the present apparatus is that the gas event is saved for later analysis and record-keeping, as well as, for verification of the event as to whether it was a true gas alarm or a false alarm provided by physical evidence of a stain development on the detection media.